Right from the start, I want to emphasize that I am not recommending treatment or making diagnoses in this post. I am asking for information. People with a number of confusing medical problems end up in the ME/CFS category, and some may have been treated with things that are not in common use. I have been given a number of anticonvulsant drugs on the suspicion that I might have a confusing type of epilepsy without obvious seizures, but I have no experience with the type I'm about to describe. This question came to me via a friend who has a solid diagnosis of a rare condition called hypokalemic periodic paralysis (PP). In my limited experience it is rare for ME/CFS patients to have actual paralysis, though there are cases with extreme weakness that may be hard to distinguish from some variants of periodic paralysis. Officially, this is a rare genetic disorder with an incidence of about 1 in 100,000. However, about 1/3 of PP patients do not have any known genetic markers. It is also common for it to appear in young adults who previously had no such illness. This could indicate an infectious origin, or the action of genes which only become active at sexual maturity. PP is a channelopathy, with potassium channels most commonly affected. We have considerable reason to suspect disturbances in ion channels and fluid regulation in ME/CFS. The FDA recently approved the first drug to treat both hypokalemic and hyperkalemic PP, Keveyis (dichlorphenamide/diclofenamide). This is a sulfonamide which acts as a carbonic anhydraze inhibitor. This class of drugs has a long and strange history. Some were synthesized around 1910, but their biological activity was not tested. In the early 1930s work on the first antibiotic, Prontosil, discovered antibacterial action with low human toxicity. Subsequent work showed that the chemical precursor sulfanilamide had better antibacterial activity. The medical story of carbonic anhydraze inhibitors mainly concerns use in epilepsy and glaucoma, though idiopathic intracranial hypertension has also been treated with these. Here is a list of some drugs in question: acetazolamide, brinzolamide, dorzolamide, methazolamide, sulthiame/sultiame, topiramate. One problem with the new approval is that the recommended treatment now appears to cost $120,000 per year. I suspect insurance will not approve this without evidence from genetic markers, which 1/3 of those diagnosed do not have. Sulthiame/sultiame is similar in biochemical activity, and much cheaper. It has been given to children with an unusual form of epilepsy for years. My question is about experience from patients here which might guide research on use of any carbonic anhydraze inhibitors for PP patients, who would not be able to afford the newly introduced drug for PP.